<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="box">
        box
    </div>
    <script>
        const box = document.getElementById('box');
        const map = new Map([
            ['name', '张三'],
            ['age', 18]
        ]);
        map.set(box, box);
        console.log(map.keys()); 
        console.log(map.values());
        console.log(map.entries());
        for (let [k, v] of map.entries()) {
            console.log(k, v);
        }
    </script>
</body>
</html>